Jarosite versus Soluble Iron-Sulfate Formation and Their Role in Acid Mine Drainage Formation at the Pan de Azúcar Mine Tailings (Zn-Pb-Ag), NW Argentina

Minerals

Jesica Murray¹  Alicia Kirschbaum¹  Bernhard Dold²  Edi Mendes Guimaraes³ 

[1] Instituto de Bio y Geo Ciencias del Noroeste Argentino-Consejo Nacional de Investigaciones Científicas y Técnicas (IBIGEO-CONICET), Museo de Ciencias Naturales, Universidad Nacional de Salta, Mendoza 2, Salta 4400, Argentina; E-Mail:;SUMIRCO (Sustainable Mining Research & Consult EIRL), Casilla 28, San Pedro de la Paz 4130000, Chile; E-Mail:;Laboratório de Raios-X, Instituto de Geociencias, Universidade de Brasilia (UnB), Brasilia 70910-900, Brazil; E-Mail:

关键词: sulfide oxidation;    mine tailings;    soluble iron-sulfate salts;    jarosite;    semi-arid climate;    metal release;    acid mine drainage;    environmental implications;   

DOI  :  10.3390/min4020477

来源: mdpi

【 摘 要 】

Secondary jarosite and water-soluble iron-sulfate minerals control the composition of acid mine waters formed by the oxidation of sulfide in tailings impoundments at the (Zn-Pb-Ag) Pan de Azúcar mine located in the Pozuelos Lagoon Basin (semi-arid climate) in Northwest (NW) Argentina. In the primary zone of the tailings (9.5 wt % pyrite-marcasite) precipitation of anglesite (PbSO₄), wupatkite ((Co,Mg,Ni)Al₂(SO₄)₄) and gypsum retain Pb, Co and Ca, while mainly Fe²⁺, Zn²⁺, Al³⁺, Mg²⁺, As^3+/5+ and Cd²⁺ migrate downwards, forming a sulfate and metal-rich plume. In the oxidation zone, jarosite (MFe₃(TO₄)₂(OH)₆) is the main secondary Fe³⁺ phase; its most suitable composition is M = K⁺, Na⁺, and Pb²⁺ and TO₄ = SO₄²⁻; AsO₄²⁻. During the dry season, iron-sulfate salts precipitate by capillary transport on the tailings and at the foot of DC2 (tailings impoundment DC2) tailings dam where an acid, Fe²⁺ rich plume outcrops. The most abundant compounds in the acid mine drainage (AMD) are SO₄²⁻, Fe²⁺, Fe³⁺, Zn²⁺, Al³⁺, Mg²⁺, Cu²⁺, As^3+/5+, Cd²⁺. These show peak concentrations at the beginning of the wet season, when the soluble salts and jarosite dissolve. The formation of soluble sulfate salts during the dry season and dilution during the wet season conform an annual cycle of rapid metals and acidity transference from the tailings to the downstream environment.

【 授权许可】

CC BY   
© 2014 by the authors; licensee MDPI, Basel, Switzerland.